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Sept. 29, 1925. 1,555,545

P. BROWN ET AL BREAKER POINT MECHANISM AND METHOD OF OPERATING THE SAME Filed June 26, 1922 ATTORNEYS Patented Sept. 29, 1925.

UNITED. STATES PATENT OFFICE.

PHELPS BROWN, HAROLD H. CLARK, TERRENCE G. LOUIS, AND IRA E. HENDRIGKSON,

OI SPRINGFIELD, MASSACHUSETTS;

SAID CLARK, SAID LOUIS, AND DRICKSON ASSIGNORS TO WICO ELECTRIC COMPANY,

SAID HEN- OF SPRINGFIELD, MASSACHU- SETTS, A CORPORATION OF MASSACHUSETTS.

BREAKER-POINT MECHANISM AND METHOD OPERATING THE SAME.

Application filed June 26, 1822. Serial No. 570,940.

To all whom it may concern:

Be it known that we, PHELPS BROWN, HAROLD H. CLARK, TERRENCE G. Lowe, and IRA E. HENDRICKSON, citizens of the United States, residing at Springfield, in the county of Hampden and State of Massachusetts, have invented new and useful Improvements in Breaker-Point Mechanism and Methods of Operating the Same, of which the following is a specification.

This invention relates to an improved breaker point mechanism and to a'method of operating the same. By breaker points, we mean the cooperating electrical contacts of interrupter mechanisms, such for example as those used in connection with ignition systems and apparatus. Our invention is, however, capable of other and more general applications wherever two cooperating and relatively movable electrical contacts are used to open and close an electrical circuit.

The general object of the invention is to provide an improved breaker point mechanism and to operate the breaker points in an improved manner with the end in view of very materially increasing their useful life and of substantially eliminating the pitting, burning, and other like troubles usually incl dentto the rapid and oft repeated opening and closing of an electrical circuit.

The invention has proved particularly useful in connection with breaker points of tungsten when used to control an ignition circuit. It undoubtedly will prove equally useful with breaker points of molybdenum or other metals or alloys having generally similar characteristics.

It is well known that the life of breaker points is comparatively short and that they constitute the weak link in ignition systems. When operated in the ordinary fashion, and by the methods heretofore prevalent, the contacting surfaces do not long remain in the ideal condition in which they are clean, bright, and in true parallelism. On the contrary, due to the fact that they are subjected to the heat of electric arcs, they are prone to become deformed, burned and pitted. Fused particles from one surface become attached to the opposite contacting surface, forming a point or projection on the latter and a craterlike pit on the former and destroying the broad, and parallel contactmg areas desired. The action described, although small at first, is cumulative. Phe resistance between the contacting surfaces 1ncreases, thus increasing the rate of their deformation, and becomes rapidly worse, eventually requiring renewal of the breaker points or refinishing of the contacting surfaces.

The metal tungsten is hard and brittle and, while by -modern developments its natural characteristics have been considerably modified so that it can be worked and has some ductility, the commercial tungsten, supplied for use as breaker points, still retams its natural characteristics to a considerable degree.

This invention proceeds along the theory of a continual working and reworking of the metal particles in the contacting surfaces of the breaker points while they are in operation. The speed at which the breaker points are moved into contact is so gauged with relation to the mass thereof as to administer a percussive blow and the characteristic feature of the invention is to properly gauge the force of this blow so that the desired results are obtained. The object, sought to be obtained, is the peaning of the misplaced particles of fused metal back into place as fast as they become mis placed and the redistribution of the particles of fused metal into parallel contacting surfaces.

The prevalent trouble with breaker points is probably due generaly to an insufiicient force of impingement of the points. The blow is not'suflicient to rework the metal particles and the contacting surfaces do not, therefore, remain clean, smooth and parallel but become roughened'and pitted, resulting in high contact resistance. The results of this invention are obtained by using a blow of greater force. The blow, however, must not be too severe and should not be any greater than is necessary to pean the particles back into place. Force, in excess of this requirement, will rapidly wear away the breaker points or may even split or chip the metal. Either of these occurrences will shorten the useful life of the breaker points just as surely as their life is shortened by the use of an insuflicient blow and the desired result can only be obtained by a blow detail with refrence to the accompanying drawings, in which:

The figure shows a sectional elevational view of an interrupter mechanism and an operating means therefor.

In this drawing, the relatively movable cooperating breaker points, or contacts, are shown at 5 and 6, respectively, the former, as shown, being fixed and the latter movable. The breaker point 5 is fixed to a support 7, as by a nut 8, and is insulated therefrom, as by the washers 9,;and bushing 10, both of suitable insulating material. Fixed to the movable point 6 is a considerable mass 11, herein shown as of cylindrical form in order to cooperate with a cylindrical bore 12 in the support 7 and guide the movable point in true straight line movement, which is preferred, although not essential to the present invention. The support 7 is shown as carried by a suitable frame A, to which it is attached, as by a drive fit of the support in a recess in the frame. The movable point 6 and its attached mass 11 may be reciprocated in any suitable way and there has been shown a rod 13 which is suitably supported and guided, as in frame A, and which is reciprocable periodically at suitably timed intervals. The rod 13 may, for example, be a part of an internal combustion engine or connected thereto in any of the various ways well. known in the art, or

may be otherwise reciprocated in any suitable manner. The rod 13 has fixed thereto a projecting arm 14.- which is provided with a recess 15 underlying the bore 12 of the support 7 A rod 16 fixed to the mass 11 depends therefrom and passes loosely through and beyond the recess 15. The mass 11 and point 6 are moved toward point 5 by the arm 14 through the intermediary of a spring 17 which is coiled around rod 16. The latter carries an abutment 18, preferably adjustable as shown, which abutment is disposed below arm 14 and is adapted to be engaged thereby to cause the separation of the breaker oints.

The interrupter mechanism described will serve as an illustrative example of one suitable type with which the invention may be used. Many and various other types of interrupter mechanism are known, with which the invention is-equally applicable, and the details of this mechanism are not .at all essential to the present invention,

which is capable of general and. much broader application. The particular mechanism referred to has'been illustrated and described in detail herein as being the tangi ble apparatus with which the experiments, resulting in the present invention, were made.

This mechanism does, however, embody several features, which, although not-essential to the present invention, are desirable, advantageous and preferred. Among these are the movement and guiding of the relatively movable breaker points into engagement with their contacting surfaces 8 mamtained in true arallelism so that an engagement of t ese surfaces is insured throughout their entire area. Also, the association with the breaker points (either one) of a spring, such as 17, in conjunction with provision for travel of the member 14: in excess of the distance between the points 5 and 6 when fully separated, is desirable because it insures that the points will be firmly pressed together during their interval of contact. This last named arrangement also allows the member 1 1 to et started in motion and acquire considera le momentum before it en ages abutment 18, the better to overcome the inertia of mass 11 and the more quickly to accelerate it,the desired result being to separate the points instantly, or as near so as can be practically obtained.

7 The present invention, depending as it does on the force of the blow administered as the points 5 and 6 come into engagement. requires essentially a consideration of the two variable factors which determine the force of the blow, vizspeed and-mass.

The result desired may be effected by varya ing either, or both, as found most convenient, until the necessary force is obtained. In the case illustrated, it has been found desirable to add the considerable mass 11 to the movable breaker point. Either or both of the points may be moved for it is the relative movement therebetween and the relative speed of the points as they move into engagement that counts. If both points move, the mass of both will, of course, need to be taken into consideration in determining the force required.

It will be apparent that no definite limits of speed and mass can be given since either or both may be varied to secure the blow desired. We are also unable to specify the force of the blow in ordinary units of measurement as the results described have been obtained by long experimentation and b the process of varying one or the other 0 the two variable factors until the desired results were obtained. Ifit were ossible to accurately measure the force of t 1e blow applied, it is quite likely that this force might very well not be the proper one for an interrupter mechanism of a different type. The force of now prevalent troubles structive effects to be repaired and the destructive effects will vary in various types of installations, For example, the capacity of the condenser which is ordinarily bridged across the breaker points for the purpose of reducing the arcing between them, is a factor in the problem controlling in some degree e amount of the destructive efiects produced.

The only feasible way, at present known to us, for securing the results described is, therefore, by experimentation and variation of the factors entering into the problem until the optimum blow is secured for the particular type of installation under considera tion. Our experiments, conducted over a long period of time, have enabled. us to secure aVproper proportioning of mass and speed ofj the breaker points for the par ticular interrupter illustrated so that what we term as the optimum blow has been obtained. Mechanisms, like that illustrated, have been set up and operated on life tests, but, as yet, We have been unable to determine the ultimate useful life of the points. Some of these tests-have already been conducted over a period of five thousand hours and bid fair to continue successfully for a much longer period. No failure of the breaker points has as yet appeared. None have become pitted, burned, or rendered any less suitable for service than they originally were. On the contrary the points still remain smooth, clean and bright, and entirely free from pits, despite the long service which they have already given. None of the points have had to be replaced or redressed, as is ordinarily necessar after a far shorter term of service than t at specified. While it is diflicult to state the average life in hours of service of breaker points, operated by methods heretofore prevalent, we do know that it is very much lower and frequently not over two hundred hours before redressing of the points is required. Our observations indicate that by the use of the optimum blow, none of the usual troubles are going to appear. In other words, the incident to breaker point operation, appear to be entirely eliminated and certainl at least so for all practical purposes. T e only effects, so far ascertained at the end of the five thousand hours of service in the tests described, is a very slow wearing away of the tungsten and we are convinced that the eventual failure fuse dress the same.

of these points will be due only to this wearing away of the metal and will occur only when the tungsten is entirely worn away. The points, therefore, appear to be good until entirely worn away and their life will thus depend on the thickness of the tungsten points and can be increased by providing tungsten of increased thickness.

We conceive that in the operation of breaker points, particles of metal in the contacting surfaces become fused for an instant and while in a fused or molten condition, they are liable to misplacement. The operationof the points is such that oft repeated melting and solidifying of the metal in the contacting surfaces occur. Particles of fused metal of one contacting surface become attached, on solidification, to the opposite contacting surface and on continued operation without any effort at redistributing the misplaced particles, the action described is cumulative and eventually results in the formation of pronounced pits and projections which increase the tendency to arc. Our invention, by the use of the blow of optimum force, causes any particles, thus misplaced, to be peaned down shortly after their misplacement into smooth parallel contacting surfaces. The points are virtually redressed at each operation and the destructive eiiects prevented from accumulating. The metal misplaced in any manner is redistributed and placed where it belongs. This is the theory of our breaker point operation, as we now understand it, but, whether or not this is the correct theory, we do know that by experimentation we have arrived at the result desired of eliminating the destructive efiects due to arcing and that we have operated our breaker points for heretofore unheard of periods without any evidence of destructive effects thereon other than the gradual wearing away of the metal above alluded to and this, as has been stated, is at a very slow rate.

We believe that we are the first to provide a breaker point mechanism of the type described and the first to operate the same in the manner herein described, and the first to obtain the novel results set forth and we desire to claim our invention in the broadest possible legal manner.

What we claim is:

1. Interrupter mechanism, comprising, relatively movable breaker points, means for moving them the one relatively to the other into and out of engagement, means for guiding the ints into contact with their contacting aces in true parallelism, and a mass fixed to one of said points sufiicient in conjunction with the speed of relative movement of the points to cause them to en age with a percussive blow, the force of w ich is snfiicient to redistribute the particles of d metal in their contacting faces and re- 2. Interrupter mechanism, comprising, relatively movable breaker points, means for moving tlmm the one relatively to the other into and on of engagement, means for guiding the oints into contact with their contacting aces in true parallelism, said guiding means permitting one of said points to turn about its axis, and a mass fixed to one of said points sufficient in conjunction with the speed of relative movement of the points to cause them to engage with a percussive blow, the force of which is sufficient to redistribute the articles of fused metal in their contacting aces and redress the same.

3. Interrupter mechanism, comprising, a cylindrical guide tube, a breaker point fixed therein, a movable breaker point, adapted to contact therewith, a cylindrical weight fixed thereto and slidably and turn ably engaged with the inner wall of said tube and serving to guide the adjacent faces of said points into contact with true parallelism, and means for moving the second named point at a speed so proportioned rela tively to said weight that it engages the first named contact with a percussive blow sufficient to redress the contacting faces by a peaning action.

4. Interrupter mechanism, comprising, relatively movable breaker points, means for moving them the one relativelyto the other into and out of engagement, means for guiding the points into contact with their contacting faces in true parallelism, a mass fixed to one of said points sufiicient in conjunction with the speed of relative movement of the points to cause them to engage with a percussive blow, the force of which is sufficient to redistribute the particles of fused metal in their contacting faces and redress the same, an operating stem on one of said points, a reciprocating member through which said stem passes freely, an abutment on the stem on one side of said member, and a spring tending to hold said member and abutment in contact and serving to absorb the shock of said percussive blow.

5. Interrupter mechanism, comprising, a cylindrical guide tube, a breaker point fixed therein, a movable breaker point,

adapted to contact therewith, a cylindrical weight fixed thereto and slidably and turnably engaged with the inner wall of said tube and serving to guide the adjacent faces of said points into contact with true parallelism, an operating stem fixed to said weight, a rigid reciprocable operating arm through which said stem freely passes, a spring between one face of said arm and weight, and an abutment on said stem adapted to be engaged by the opposite face of said arm.

In testimony whereof we have affixed our signatures.

PHELPS BROWN. HAROLD H. CLARK. I IRA E. HENDRIOKSON. TERRENOE G. LOUIS. 

